As optical fiber capacity grows, it is becoming important to monitor and detect transmission degradations in optical fiber in real time. In an exemplary embodiment, more and more optical systems are relying on Raman amplification to extend reach, distance, and/or capacity. This requires optical fiber that exhibits good qualities as a transmission medium, i.e. low back reflection, low connector loss, etc. Conventional monitoring systems and methods can utilize commercial Optical Time Domain Reflectometers (OTDRs). Conventional OTDRs use broad spectrum light sources such as Fabry-Perot lasers that have multiple longitudinal lasing modes. Disadvantageously, conventional OTDRs are bulky and exhibit high cost. To reduce cost, it is possible to use Integrable Tunable Laser Assembly (ITLA), Externally Modulated Laser (EML), Distributed Feedback (DFB), or the like as a source to make an on-board, low cost OTDR-like monitoring device to perform optical fiber quality checks. However, due to narrow line-width (in the range of few hundred kHz to a few MHz) of ITLA, EML, DFB, etc. sources, this narrow line-width causes coherence effects in detected Rayleigh scattering signals making the OTDR measurements unreliable. There exists a need for a simple approach in reducing the coherence effects due to narrow line-width from ITLA, EML, DFB, etc. sources.